Having established that a substantial portion of OCD traces to common variation, we next addressed an important issue about its nature. Specifically, in an earlier study, Davis et al. (5) found that alleles with MAF < 0.05 did not contribute meaningfully to the heritability of OCD (0.0001% of total heritability). To compare our results to those in Davis et al. (5), we estimated the portion of total heritability for groups of autosomal SNPs with distinct allele frequencies, grouping the SNPs into six bins based on their MAF (Figure 1; Table S9): 0.01–0.05, 0.05–0.1, 0.1–0.2, 0.2–0.3, 0.3–0.4, and 0.4–0.5. For all the bins, we included the first six PCAs as covariates and set population prevalence to 0.01. Estimates of the portion of total heritability for the bins were distributed differently between these two studies (Figure 1; Table S9). Curiously, although the total heritability of the first two bins (MAF < 0.1) was similar across studies, 2.6% for our study versus 4% for Davis, estimates for specific bins were not similar; in the Davis et al. study, the MAF bin from 0.01–0.05
